1. Field of the Invention
The present invention relates to a structure which can be used in reactions wherein the reaction and distillation of the reaction system are carried on concurrently using the structure as both catalyst for the reaction and as a distillation structure.
2. Related Art
U.S. Pat. No. 4,215,011 discloses a plurality of closed cloth pockets containing a particulate catalytic material arranged and supported by wire mesh. U.S. Pat. No. 4,250.052 discloses distillation packing structure consisting of sulfonated cation resin.
U.S Pat Nos. 4,232,177 and 4,242,530 disclose the use of such structures for various catalytic reaction processes. U.S. Pat. No. 2,403,672 functionally states that the catalyst serves as the packing material in the column to fractionate the reaction products, however, no indication of the physical means to obtain this is disclosed.
U.S. Pat. No. 4,443,559 discloses catalytic distillation structures for use in reaction distillation columns. These catalytic structures being in the shape of a single cylinder, sphere, doughnut, cube, or tube.
The present invention provides a catalytic distillation structure for use in reactions, which can be used as a distillation structure. In order to serve both functions, it has been found that the structure must meet three criteria. First, the structure must be such as to provide for even spatial dispersement in the reactor distillation column. That is, the catalyst structures must rest in the column in a geometric arrangement which will perform the desired functions of reaction and distillation sites. To achieve this the structure must be such as to provide fairly uniform spatial distribution in the column.
A second criteria is that there must be sufficient free space in the catalyst bed to allow for the liquid phase surface contact and vapor phase distillation with the concurrent separation of the material in the column by the distillation into vapor and liquid phases. It has been observed that in the catalyst bed a free space of about 50 volume % is adequate to obtain an operable fractionation.
A third criteria is the necessity for the catalyst bed to b able to expand and contract as it must during use without undue attrition of the catalyst.
These criteria have been met in the structures described and used in U.S. Pat. Nos. 4,242,530; 4,232,177; 4,250.052, 4,215,011 and 4,443,559 described above.